Optical weft stop motion for a weaving machine

ABSTRACT

The beam is caused to move through an angle to cover the area in which a weft yarn may be displaced. Detection of a weft yarn in this area allows continued operation of the weaving machine whereas absence of the weft yarn causes the weaving machine to shut down. The means to move the light beam is synchronized with the weaving machine drive.

United States Patent lnventor Erwin Phrrwaller Winterthur, Switzerland Appl. No. 818,636

Filed Apr. 23, I969 Patented July 6, 1971 Assignee Sulzer Brothers, Ltd.,

Winterthur, Switzerland Priority Apr. 26, 1968 Switzerland 6295/68 OPTICAL WEFT STOP MOTION FOR A WEAVING MACHINE 10 Claims, 3 Drawing Figs.

US. Cl 139/370 lnt.Cl 00311 51/34 Field of Search 28/51 [5 6] References Cited UNITED STATES PATENTS 3,139,911 7/1964 Breitmeier 139/370 3,379,225 4/1968 lchimi m1. 139/353 3,489,910 1/1970 Bohme et al 139/370 x FOREIGN PATENTS 460,664 7/1968 Switzerland 139/370 Primary Examiner-Henry S. .laudon Attorney-Kenyon, Kenyon, Reilly, Carr 8L Chapin ABSTRACT: The beam is caused to move through an angle to cover the area in which a weft yarn may be displaced. Detection of a weft yarn in this area allows continued operation of the weaving machine whereas absence of the weft yarn causes the weaving machine to shut down. The means to move the light beam is synchronized with the weaving machine drive.

PATENTFU JUL 61% 3,590,882

sum 1 (IF 2 Fig. 1

7 Z7 Z5 .9 1' g g llllll Inventor:

EDWIN PFARF? WAL LER HTTO NETS S OPTICAL WEFT S'IOI MOTION F011 A WEAVING MACHINE This invention relates to an optical weft stop motion for a weaving machine.

Heretofore, it has been known to provide weaving machines with weft stop motions which rely on light beams to deactivate the weaving machine in the case of weft yarn break. For example, one such motion emits a light beam from a transmitter in a direction transverse to a weft yarn, reflects the light beam from a mirror situated behind the weft yarn position in the event the weft yarn is missing, and after further reflection pro jects the light beam to a photoelectric cell which initiates switching operations to stop the weaving machine. If the weft yarn is present, the beam is interrupted by the weft so as not to reach the photoelectrical cell. Thus, the photoelectric cell does not initiate any switching operations to stop the weaving machine.

However, in these known systems, the beam may not reliably meet the weft yarn, because the weft yarn may not be situated exactly in the picking line, particularly when thin weft yarns are being used. As a result, the weaving machine may be stopped incorrectly.

Accordingly, it is an object of the invention to avoid inadvertent stopping of a weaving machine when a weft yarn is out of alignment.

It is another object of the invention to provide a weft stop motion for detecting the presence of a weft yarn in a range of positions outside a picking line.

Briefly, the invention provides an optical weft stop motion for a weaving machine which functions to detect the presence of a weft yarn within a range of possible positions. The weft stop motion includes a transmitter which is mounted on the weaving machine in a position to emit a light beam transversely of the picking line of the weft yarn which is drawn through the shed by a shuttle. The transmitter is further constructed so that the light beam can be moved in a searching pattern transversely of the weft yarn so as to impinge on a weft yarn which may be located outside the picking line. The stop motion also includes a receiver which is mounted in alignment with the light beam to receive the light beam from any point in the searching pattern should the weft yarn be absent and to generate a signal in response to the reception of the beam so as to initiate stoppage of the weaving machine.

The searching pattern of the light beam can also be limited in range so that the weaving machine is stopped when a weft yarn passes too far outside the picking line since this is frequently an indication of a broken weft yarn.

These and other objects and advantages of the invention will become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a general front view of a weaving machine from the fabric side which incorporates a weft stop motion according to the invention;

FIG. 2 illustrates a plan view of the stop motion receiver of the invention in relation to the picking line; and

FIG. 3 illustrates a view of the stop motion taken in the direction of arrow A in FIG. 2.

Referring to FIG. 1, the weaving machine which is of known construction includes a pair of side supports 1, 2 between which a warp beam (not shown), a cloth beam 3, guide and tensioning means for the warp and fabric, a central member 4 connecting the supports 1, 2 and a main drive 5 for the machine are disposed. In addition, a shedding mechanism having a heedle forming part and a reed 7 are disposed between the supports 1, 2.

A picking mechanism 8 which projects a shuttle is mounted on one side support 1 while the opposite support 2 of the machine carries a catching mechanism 9 which catches the shuttle at the end of a picking operation. A weft yarn 10 is supplied from a supply bobbin 11, which is usually fixed outside the shed, and is directed via a screen 12 and a yarn tensioner 13, which moves up and down, to enter a shed 14 (FIG. 3).

During a picking operation, the shuttle 9a moves toward the catching mechanism 9 while directing the weft yarn 10 through a picking line 22. After the picking operation (FIG. 2), the shuttle 9a is pushed back slightly in the catching mechanism 9 so as to have exactly the same position on each pick. The yarn tensioner 13 is moved into the top position in these conditions so that the weft yarn is always tensioned on the subsequent return movement of the shuttle. During the return movement of the shuttle 9a, yarn brakes (not shown) ensure that the resulting yarn deviation at the yarn tensioner 13 is formed primarily by withdrawing the entire inserted weft yarn, if necessary, a certain amount of yarn is also drawn from the bobbin 11 at the same time.

After the return movement of the shuttle and weft yarn, the weft yarn is cut on the picking side by shears (not shown). The projecting weft yarn ends on both sides of the shed are then tucked into the next shed by a selvedge forming mechanism after beating up and shedding. The fabric is then wound on the cloth beam. The reed 7 and a shuttle guide formed from a number of guide teeth 15 (FIG. 2) are disposed on a sley. The warp and the fabric move in the direction of the arrow 17.

Referring to FIGS. 2 and 3, the weft stop motion includes a stay 20 which is secured to the catching mechanism 9 and which supports a reflector 21 thereon the form of a strip. The reflector strip 21 is disposed beneath the weft line 22 and perpendicularly thereto and is, for example, of the type known by the registered Trade Mark "Scotchlite" which consists of a number of small spherical lenses which are disposed on a substrate and which, of course, have the property of reflecting in themselves any beam entering through the center point. The stop motion also includes a housing 25 mounted above the picking line 22 which contains a transmitter or light source 26, a permeable mirror 27 and a photoelectric cell 28. The light emitted by the light source 26 is focused by known means into a sharp beam 29, the diameter of which is of the order of magnitude of the diameter of the weft yarn used, and the beam 29 is passed through the mirror 27 and meets the reflector 21 which reflects the beam as explained above. After reflection at the mirror 27, the beam is projected in the form of a beam 30 on to the photoelectric cell 28.

In order to move the light beam 29 through a searching pattern transversely of the picking line 22 and along the reflector strip 21, the housing 25 is pivotally mounted on the catching mechanism 9 about an axis 31 extending perpendicularly to the drawing plane, and is connected to a pivot 35 via a lever system formed by three pivotally interconnected levers 32, 33, and 34. The pivot 35 is so coupled with the weaving machine drive that the housing 25 performs an oscillatory movement after each picking operation in synchronism with the drive. In those conditions, the beam 29 swings back and forth through an angle a to cover a search zone 36 extending around the weft picking line 22, i.e. the path theoretically covered by the shuttle. At the same time, the reflected beam 30 impinges on the photoelectric cell 28 so that the output terminals of the cell 28 produce a voltage resulting in a current flowing through a connected relay (not shown). This relay has a timelag response so as not to actuate its contact until a given time has elapsed. The relay contact is situated in the weaving machine drive motor control circuit.

During use of the optical weft stop motion, a weft yarn 10 will normally be situated within the search zone 36, so that whenever the beam 29 is interrupted on the passage of the weft yarn, the beam will not be reflected by the reflector 21 and will not reach the photoelectric cell 28. The current through the relay is thus interrupted twice on each search movement of the beam. The relay response lag is so selected that the relay does not respond if there is a weft yarn present in the search zone. Consequently, the relay contact in the motor central circuit is not actuated and no switching operations are initiated to stop the machine. On the other hand, if there is no weft yarn within the search zone 36, the beam 29 is not interrupted and the current flowing through the relay during the entire period of a search movement is sufficient to close the relay contact and thus initiate stoppage of the weaving machine.

Instead of the housing 25 performing a complete oscillatory movement after each picking operation as described above, this oscillatory movement can be divided up over two picking operations. The forward movement of the housing then provides the scanning required after one picking operation while the return movement provides the scanning required after the next picking operation. The frequency of oscillation of the housing can thus be halved which is an advantage in highspeed weaving machines. The relay response time must also be reduced accordingly.

The invention thus provides an optical weft stop motion which is capable of detecting the presence of a weft yarn even though the yarn may be displaced from the usual picking line.

lclaim:

1. An optical weft stop motion for a weaving machine comprising: a housing disposed for rotation about an axis running parallel to the picking line of the weft yarn, and comprising a transmitter for emitting a beam transversely of the picking line of a weft yarn in the machine, a permeable mirror and a receiver positioned with respect to said transmitter to receive said beam in the absence of the weft yarn and to initiate stopping of the weaving machine in response to the receiving of said beam, and means coupled to said housing for imparting thereto a rotational oscillatory motion about said axis.

2. An optical weft stop motion as set forth in claim I which further comprises a reflector spaced from said transmitter on the opposite side of the picking line to receive and reflect said beam with said permeable mirror being positioned between said transmitter and reflector for passage of said beam from said transmitter therethrough and for reflecting the reflected beam from said reflector to said receiver.

3. An optical weft stop motion as set forth in claim 1 wherein said means moves said beam through half an oscillation after one pick and through the remaining half of the oscillation after a second pick.

4. An optical weft stop motion for a weaving machine having a weft yarn directed through a picking line comprising a transmitter for emitting a beam transversely of the picking line to impinge on a weft yarn therein;

means for moving said beam transversely of said picking line through a search zone extending on opposite sides of said picking line to impinge on a weft yarn in said search zone;

an elongated reflector mounted in a stationary position with respect to said picking line on the opposite side of said picking line from said transmitter for reflecting said beam in the absence of a weft yarn therebetween; and

a receiver on the same side of said picking line as said transmitter for receiving the reflected beam from said reflector to initiate stoppage of the weaving machine in response to the reception of the reflected beam.

5. An optical weft stop motion as set forth in claim 4 which further comprises a housing containing said transmitter and said receiver therein, said housing being pivotally mounted about an axis parallel to said picking line and wherein said means is connected to said housing to oscillate said housing about said axis.

6. An optical weft stop motion as set forth in claim 5 wherein said means is further connected to the main drive of the weaving machine to oscillate said housing in synchronism therewith.

7. An optical weft stop motion as set forth in claim 5 wherein said axis passes through said housing.

8. An optical weft stop motion for a weaving machine comprising: a housing disposed for rotation about an axis parallel to the picking line of a weft yarn in the machine; a transmitter mounted in said housing for emitting a beam transversely of the picking line; a receiver positioned with respect to said transmitter to receive said beam in the absence of the weft yarn and to initiate stoppage of the weaving machine in response to the receiving of said beam; a permeable mirror between said transmitter and said receiver for passage of said beam from said transmitter therethrough and for reflecting the transmitted beam to said receiver; and means coupled to said housing for lmpartmg a rotational oscillatory motion to said housing about said axis whereby said beam is given a searching movement transversely of the picking line to intercept a weft yarn located in the path of said beam.

9. An optical weft stop motion as set forth in claim 8 wherein said axis is located within the housing.

10. An optical weft stop motion as set forth in claim 8 wherein said axis coincides with the plane of the permeable mirror. 

1. An optical weft stop motion for a weaving machine comprising: a housing disposed for rotation about an axis running parallel to the picking line of the weft yarn, and comprising a transmitter for emitting a beam transversely of the picking line of a weft yarn in the machine, a permeable mirror and a receiver positioned with respect to said transmitter to receive said beam in the absence of the weft yarn and to initiate stopping of the weaving machine in response to the receiving of said beam, and means coupled to said housing for imparting thereto a rotational oscillatory motion about said axis.
 2. An optical weft stop motion as set forth in claim 1 which further comprises a reflector spaced from said transmitter on the opposite side of the picking line to receive and reflect said beam with said permeable mirror being positioned between said transmitter and reflector for passage of said beam from said transmitter therethrough and for reflecting the reflected beam from said reflector to said receiver.
 3. An optical weft stop motion as set forth in claim 1 wherein said means moves said beam through half an oscillation after one pick and through the remaining half of the oscillation after a second pick.
 4. An optical weft stop motion for a weaving machine having a weft yarn directed through a picking line comprising a transmitter for emitting a beam transversely of the picking line to impinge on a weft yarn therein; means for moving said beam transversely of said picking line through a search zone extending on opposite sides of said picking line to impinge on a weft yarn in said search zone; an elongated reflector mounted in a stationary position with respect to said picking line on the opposite side of said picking line from said transmitter for reflecting said beam in the absence of a weft yarn therebetween; and a receiver on the same side of said picking line as said transmitter for receiving the reflected beam from said reflector to initiate stoppage of the weaving machine in response to the reception of the reflected beam.
 5. An optical weft stop motion as set forth in claim 4 which further comprises a housing containing said transmitter and said receiver therein, said housing being pivotally mounted about an axis parallel to said picking line and wherein said means is connected to said housing to oscillate said housing about said axis.
 6. An optical weft stop motion as set forth in claim 5 wherein said means is further connected to the main drive of the weaving machine to oscillate said housing in synchronism therewith.
 7. An optical weft stop motion as set forth in claim 5 wherein said axis passes through said housing.
 8. An optical weft stop motion for a weaving machine comprising: a housing disposed for rotation about an axis parallel to the picking line of a weft yarn in the machine; a transmitter mounted in said housing for emitting a beam transversely of the picking line; a receiver positioned with respect to said transmitter to receive said beam in the absence of the weft yarn and to initiate stoppage of the weaving machine in response to the receiving of said beam; a permeable mirror between said transmitter and said receiver for passage of said beam from said transmitter therethrough and for reflecting the transmitted beam to said receiver; and means coupled to said housing for imparting a rotational oscillatory motion to said housing about said axis whereby said beam is given a searching movement transversely of the picking line to intercept a weft yarn located in the path of said beam.
 9. An optical weft stop motion as set forth in claim 8 wherein said axis is located within the housing.
 10. An optical weft stop motion as set forth in claim 8 wherein said axis coincides with the plane of the permeable mirror. 